Journals >Acta Photonica Sinica
Contents
2018
Volume: 47 Issue 6
30 Article(s)
Export citation format
Gluing Method of Detected Signal Based on Lidar
FENG Chang-zhong, WU Song-hua, and LIU Bing-yi
A data gluing method of quadratic polynomial fitting for lidar signal detection is proposed referring to the small gluing region and singular points. The data gluing region is extended to fully take the non-linear relationship between analog-to-digital and photon counting into account. The influence of cloud height on A data gluing method of quadratic polynomial fitting for lidar signal detection is proposed referring to the small gluing region and singular points. The data gluing region is extended to fully take the non-linear relationship between analog-to-digital and photon counting into account. The influence of cloud height on data quality is analyzed and the quality control is implemented to obtain stable gluing coefficient. The pile-up photon counting data is corrected according to the computational non-linear relationship between analog-to-digital and photon counting data. The synchronous comparison experiment between direct-detection Doppler lidar and balloon was carried out to verify this modified gluing method. The result shows that correlation coefficient increases from 0.80 to 0.85, the root mean square error decreased from 3.37 m/s to 2.41 m/s, and the deviation decreased from 0.60 m/s to 0.06 m/s. The result demonstrates that the modified gluing method could improve the accuracy of wind field detected by direct-detection Doppler lidar and is useful for atmosphere detection lidar to glue far-field and near-field signal..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 601001 (2018)
Simulated Experiment of the Light Intensity Influenced by Non-Kolmogorov Turbulence
ZHANG Na-na, SHAN Xin, ZHANG Yan-ge, FENG Yang, and GUO Song
A Non-Kolmogorov turbulence simulation experiment was carried out in the laboratory, based on the liquid crystal spatial light modulator. The probability density distribution, the scintillation index and the temporal powerspectrum were analyzed, and the experimental results were compared with the the turbulence theory.A Non-Kolmogorov turbulence simulation experiment was carried out in the laboratory, based on the liquid crystal spatial light modulator. The probability density distribution, the scintillation index and the temporal powerspectrum were analyzed, and the experimental results were compared with the the turbulence theory. The results show that the probability density distribution of the normalized logarithmic intensity is more close to the normal distribution under weak turbulence, and the fitting coefficient becomes larger with the decrease of the turbulence strength. In the high frequency band of the intensity temporal power spectrum, the power law reduces as the turbulence spectral power law decreases. Although its value is less than the theoretical analysis, the variation trend does match the theory.The scintillation index decreases with the increase of the atmosphere coherence length. It changes abruptly when the atmosphere coherence length is less than 0.05 m, while it tends to change flattenedly when the atmosphere coherence length is greater than 0.2 m. This changing trend remains the same under different Non-Kolmogorov turbulence spectrum, which is also consistent with the theoretical prediction. The results illustrates that the turbulence simulation experiment can reproduce the turbulence effect on the received light intensity in wireless optical communications. Moreover, the error analysis of the simulation experiment illustrates that the main sources of the experimental error are different under different turbulence strength. It can provides some effective advices for the improvement of further experiments..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 601002 (2018)
System Analysis of Ground-based Inverse Synthetic Aperture Lidar for Geosynchronous Orbit Object Imaging
HU Xuan, LI Dao-jing, FU Han-chu, and WEI Kai
In this paper, the ground-based inverse synthetic aperture lidar for geosynchronous orbit objects imaging is analyzed. The motion characteristics and observation geometric of geosynchronous orbit objects are discussed and the system parameters of inverse synthetic aperture lidar are analyzed. The waveform is chosen to In this paper, the ground-based inverse synthetic aperture lidar for geosynchronous orbit objects imaging is analyzed. The motion characteristics and observation geometric of geosynchronous orbit objects are discussed and the system parameters of inverse synthetic aperture lidar are analyzed. The waveform is chosen to be acyclic phase-coded signal. A signal coherence preserving method based on both transmitting and local oscillator reference channels is proposed. Since the object has both vibration and three-dimensional rotation, the motion phase error estimation and compensation are implemented based on orthogonal baselines interferometry processing. The adaptive optics system is introduced to complete the time-varying phase error correction, which results from atmospheric turbulence. Moreover, it’s clarified that the inverse synthetic aperture lidar based on orthogonal baselines interferometry processing and the adaptive optics are complementary in the atmospheric correction. A preliminary system scheme is designed and simulation results show that the target vibration and three-dimensional rotation have a significant influence on inverse synthetic aperture lidar imaging..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 601003 (2018)
Optical Correlation Based Demodulator for Fiber-optic Fabry-Perot Sensor
CHEN Ke, GUO Min, WANG Ze-lin, LIU Bo-wen, ZHOU Xin-lei, and YU Qing-xu
In view of the complicated structure and high cost of the ever reported fiber-optic Fabry-Perot (F-P) sensing demodulator, a new demodulation scheme based on optical correlation is presented in this paper. A glass wafer is used as an optical cross-correlator. The cavity length of the F-P sensor is demodulated by the crIn view of the complicated structure and high cost of the ever reported fiber-optic Fabry-Perot (F-P) sensing demodulator, a new demodulation scheme based on optical correlation is presented in this paper. A glass wafer is used as an optical cross-correlator. The cavity length of the F-P sensor is demodulated by the cross-correlation relationship between the glass wafer and the F-P cavity. To optimize the optical path, the single-mode fiber-optic F-P sensing demodulator with a simple structure has been constructed by establishing a simulation model. The demodulator consists of a broadband light source with the center wavelength of 850 nm, a glass wafer, a linear CCD, a cylindrical mirror and a single-mode fiber. Experimental results show that the resolution of the demodulated cavity length is achieved to be 0.72 nm. The proposed demodulator has broad prospects in the fields of well logging, liquid level monitoring and structural health monitoring for temperature, pressure and displacement measurements..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 606001 (2018)
New Understanding of "Mode Transition" of Coated Long Period Fiber Grating
GU Zheng-tian, and FENG Wen-bin
Based on the concept of effective refractive index and the power density distribution of cladding mode, this paper re-survey the phenomenon of "mode conversion" of long-period fiber grating (LPFG), and gives new physical image for "mode conversion". By modifying the range of the effective refractiveBased on the concept of effective refractive index and the power density distribution of cladding mode, this paper re-survey the phenomenon of "mode conversion" of long-period fiber grating (LPFG), and gives new physical image for "mode conversion". By modifying the range of the effective refractive index of cladding mode of LPFG, it is pointed out that the step-like growth of the effective refractive index is the self-property of each cladding mode and there is no replacement between high and low order modes, and we rename the "mode conversion region" to "mode barrier region". It is pointed out that the incorrectness of the argument that the lower order cladding modes will guided in the overlay in the "mode transition" region by analyzing the power density distribution of cladding mode. The research in this paper shows that when the thickness of overlay reaches a certain value, the power distribution of the cladding will be more concentrated in the overlay, but the cladding mode will not be guided in overlay. This paper discusses the optimization of overlay parameters of long-period fiber grating sensors, and compares the optimization results before and after the modification of effective refractive index of cladding mode, the result shows that there is a large deviation between the optimization results of these two cases. The correctness of the optimization results after modifying the effective refractive index range is explained mechanistically, which provides the new theoretical guidance for designing high-sensitivity long-period fiber grating sensors..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 606002 (2018)
Similarity Demodulation Method of Interferometric Fiber Optic Sensing System
PANG Shuo, LUO Zheng-chun, CHANG Tian-ying, YU Miao, WANG Zhong-min, CHEN Jian-dong, WANG Yang-yang, GAO Lu, and CUI Hong-liang
A new similarity demodulation method in fiber optic sensing system based on a frequency-swept laser and a Mach-Zehnder interference structure is proposed and demonstrated. The method is designed specifically to overcome the difficulty due to the finite frequency steps of the frequency-swept laser, which is not fine enoA new similarity demodulation method in fiber optic sensing system based on a frequency-swept laser and a Mach-Zehnder interference structure is proposed and demonstrated. The method is designed specifically to overcome the difficulty due to the finite frequency steps of the frequency-swept laser, which is not fine enough and will result in inaccurate demodulation result of the interference arm length difference. The method relies on the construction of a simulated function by finely subdivide in the frequency step range, and then compare it with the real interference signal, the simulated interference arm length difference corresponding to the maximum similarity is considered closest to the true result. The feasibility of the method is verified by simulation and experiments, which show that the demodulation range of the interference arm length difference of the system is 2~17 mm, and the minimum resolution of the demodulation result over this entire range is 1 μm, corresponding to a resolution of 1/10 000th of the full scale. In addition, the method also features high anti-interference ability, and can perform demodulation satisfactorily as long as the signal-to-noise ratio is greater than 6.87 dB. According to the principle of the new demodulation scheme, in applications that do not emphasize real-time performance, the resolution of the system can be further improved by increasing the subdivision..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 606003 (2018)
Technical Research on Optical Gain Switch in Optical Packet Switching Network
LI Min-xuan, FENG Huan, WANG Huan, and XIE Xiao-ping
Since the number of switching hops are severely restricted by the insertion loss of optical switches in an optical packet switching network. A two-cascaded optical gain switch based on four-wave mixing nonlinear effects in semiconductor optical amplifiers was investigated. By using this method, the quality of output si Since the number of switching hops are severely restricted by the insertion loss of optical switches in an optical packet switching network. A two-cascaded optical gain switch based on four-wave mixing nonlinear effects in semiconductor optical amplifiers was investigated. By using this method, the quality of output signal from the optical switching will be improved as well as achieving the shape regeneration and power compensation, which means the limitation could be overcomed. The result from the OPTISYSTEM simulation platform shows that, in an optimization system, the maximum of the gain is more than 25 dB, meanwhile the bit error rate and Q factor could gain a high promotion (from 10－5 to 10－18 and 4.16 to 8.71, respectively), with the pump wavelength located at the center wavelength of the signal light within ±4 nm, the power ranging from 3 dBm to 15 dBm. This optical gain switch system will have great application prospect in optical packet switching network with multi-hops..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 606004 (2018)
Hyperspectral Image Classification with Combination of Sparse Characteristic and Neighborhood Similarity Metrics
LIU Jia-min, ZHANG Li-mei, SHI Guang-yao, and HUANG Hong
The traditional sparse representation classification methods only exploit the sparse property while they ignore the neighborhood similarity information in hyperspectral image. To address this problem, a novel sparsity-neighborhood metric classification method was proposed in this paper. Firstly, the proposed algorithm The traditional sparse representation classification methods only exploit the sparse property while they ignore the neighborhood similarity information in hyperspectral image. To address this problem, a novel sparsity-neighborhood metric classification method was proposed in this paper. Firstly, the proposed algorithm utilizes sparse representation to reveal the sparse properties of data, the following sparse similarity can be calculated in each class of samples. Then, according to neighborhood information, the method constructs the sparsity-neighborhood similarity relationship in each class of samples. Finally, the land cover types can be obtained with the federated sparsity-neighborhood similarity. The proposed algorithm possesses sparse property and neighborhood information, which can enhance the discrimination among different land cover classes to improve the classification performance. The experiments were performed on the Indian Pines and PaviaU hyperspectral data sets. Experimental results demonstrate that the proposed algorithm has better classification accuracy than other algorithms, the overall classification accuracies reach 81.69% and 86.59%, respectively. The proposed algorithm can obtain more homogeneous regions and improve classification accuracy and Kappa coefficient..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 610001 (2018)
Fusion of Infrared and Visible Images Based on Non-subsampled Contourlet Transform and Intuitionistic Fuzzy Set
CAI Huai-yu, ZHUO Li-ran, ZHU Pan, HUANG Zhan-hua, and WU Xiao-yu
Considering the traditional image fusion methods easily reduce the contrast and sharpness of image, blur edge and loss details, a fusion method of infrared and visible images is proposed based on intuitionistic fuzzy set and regional contrast in the fusion framework of non-subsampled contourlet transform. Firstly, the Considering the traditional image fusion methods easily reduce the contrast and sharpness of image, blur edge and loss details, a fusion method of infrared and visible images is proposed based on intuitionistic fuzzy set and regional contrast in the fusion framework of non-subsampled contourlet transform. Firstly, the high and low frequency components of source images are obtained by using non-subsampled contourlet transform. Then the low frequency components are combined by intuitionistic fuzzy set including double-Gaussian function due to the characteristic that intuitionistic fuzzy set can describe the fuzzy concept flexibly and accurately. The high frequency components are combined by regional features contrast and Euclidean distance method because of the feature that the method can describe the image texture information in detail. Finally the fusion image is obtained by performing inverse non-subsampled contourlet transform. The experimental results show that the proposed fusion method outperforms traditional methods which deepens the contrast of images, retains the edge and detail information in the source image, and has a better evaluation value..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 610002 (2018)
Tomographic 3D Display and Imaging Optimization
ZHOU Yun-feng, XU Liang, LI Hai-feng, and LIU Xu
In order to enhance the imaging quality of tomographic 3D display technique, the original light field was firstly reconstructed with acrylic panels and films before exerting adjustments. The freedom for adjusting display quality was expanded by adding layer weight and light field weight as factors, enabling the displayIn order to enhance the imaging quality of tomographic 3D display technique, the original light field was firstly reconstructed with acrylic panels and films before exerting adjustments. The freedom for adjusting display quality was expanded by adding layer weight and light field weight as factors, enabling the display quality to be changed while external factors remain stable. The mutual independence of line images under a horizontal parallax circumstance was confirmed, and thus a line division method was applied in the calculation to eliminate the time complexity of the fitting proceed. As the memory is saved and efficiency is enhanced, it is possible to achieve more accurate calculation in limited time. Given other factors are determined, the maximum resolution of images to be calculated under the original method is 900×1 200 pixel, but the line division method is able to calculate 1 800×2 400 pixel images without memory overflow. The evaluation standard of the effect of image reconstruction is established based on the image variance, under which it is found that increasing resolution and layer number, decreasing field of view or balancing layer weight can enhance holistic reconstruction quality, and the quality of a certain angle of view can be promoted by adding to its light field weight correspondingly. Parallax is observed in a fabricated 3-layer model with 1mm layer distance, denoting the distinguished advantage of tomographic 3D display in the reconstruction of light field..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 610003 (2018)
Image Defogging Algorithm Based on Opening Dark Channel and Improved Boundary Constraint
YANG Hong, and CUI Yan
The fog image is divided into non-sky area and sky area. For the non-sky area, a method of optimization of dark channel prior thought, namely the opening dark channel algorithm, is presented. For the sky area, an improved boundary constraint algorithm is put forward by introducing bilateral filter algorithm which has tThe fog image is divided into non-sky area and sky area. For the non-sky area, a method of optimization of dark channel prior thought, namely the opening dark channel algorithm, is presented. For the sky area, an improved boundary constraint algorithm is put forward by introducing bilateral filter algorithm which has the role of edge-preserving and denoising. The two different algorithms are utilized to estimate the more accurate transmission map in their own areas respectively. Afterwards, the two defog area can be obtained by exploiting the atmospheric physical scattering model. Finally, the haze image is restored by combining the two defog areas. The experimental results show that the proposed algorithm has greatly improve the image contrast and ameliorate the color distortion problem in haze images, especially for haze images which contain the sky area..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 610004 (2018)
Development of Diffraction Phase Microscopy and Its Quantitative Investigation of Giardia Lamblia
YANG Gang, DUAN-MU Qing-duo, LI Feng, YANG Li-mei, and HUANG Wei
Based on the principles of off-axis interferometry and common-path geometry, a laser diffraction phase microscopy system is designed and built up, and the spatial noise standard deviation of the system without sample is measured as 6.70 nm. Standard polystyrene spheres with diameter of 4.8 μm are used as the calibratioBased on the principles of off-axis interferometry and common-path geometry, a laser diffraction phase microscopy system is designed and built up, and the spatial noise standard deviation of the system without sample is measured as 6.70 nm. Standard polystyrene spheres with diameter of 4.8 μm are used as the calibration samples, the measured phase shift error does not exceed 4% compared to the expected results. 100 Giardia lamblia cysts are measured using this system and the unwrapped phase images are reconstructed, the dry mass of each cyst is estimated on the basis of phase image. Statistical analysis results indicate that shape of Giardia lamblia cysts appear to be elliptical, the major and minor diameters of cysts range from 8μm to 15 μm and 4 μm to 7 μm respectively, and the dry mass is calculated to be in the range from 42.70 pg to 137.07 pg. The proposed diffraction phase microscopy has a fast acquisition speed and a high accuracy and can meet the requirements of the quantitative analysis of morphology and dry mass of the single protozoan parasite..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 611001 (2018)
Real-time Imaging Distortion Correction of Large-field Objective Lens Based on CPU+GPU Hybrid Platform
LI Ming-jie, HU Ming-yong, ZHANG Jian, CAO Ming-po, and WANG Wei
To solve the real-time imaging distortion correction problem of industrial wide-field objective lens, a correction algorithm and CPU+GPU parallel acceleration scheme was proposed. Firstly, a distortion correction model of aspheric surface is established according to the optical distortion theory and the camera calibratTo solve the real-time imaging distortion correction problem of industrial wide-field objective lens, a correction algorithm and CPU+GPU parallel acceleration scheme was proposed. Firstly, a distortion correction model of aspheric surface is established according to the optical distortion theory and the camera calibration technology. Secondly, a correction algorithm is designed by using optical center and estimating distortion coefficients. Finally, based on the CPU+GPU hybrid acceleration platform, the kernel adaptive dimension algorithm is designed and the optimized running program is proposed, combined with OpenGL driver for real-time correction and displaying. The experimental results show that the real-time correction system can achieve a correction rate of 98.2%, single frame time-consuming of 0.026 s, the average overall speedup of 29.1 for high resolution distortion imaging. The imaging system is higher precision, transplantable and more simple, and can be widely used in the real-time imaging distortion correction..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 611002 (2018)
Filtering for Drift Data of Laser Doppler Velocimeter Based on Metabolic Double Time Series Model
WANG Qi, GAO Chun-feng, ZHOU Jian, WEI Guo, NIE Xiao-ming, and LONG Xing-wu
To reduce the random drift of a laser Doppler velocimeter effectively and improve its measurement accuracy, a metabolic double time series model based on the traditional time series model is put forward for filtering drift data of a laser Doppler velocimeter. The model consists of a cascade of two metabolic time seriesTo reduce the random drift of a laser Doppler velocimeter effectively and improve its measurement accuracy, a metabolic double time series model based on the traditional time series model is put forward for filtering drift data of a laser Doppler velocimeter. The model consists of a cascade of two metabolic time series models, each of which models 13 data points using a time series model in turn. The static and dynamic drift data of a laser Doppler velocimeter are modeled and filtered based on the model respectively. The variance analysis method and the Allan variance method are used to analyze the static drift data before and after being modeled and filtered. The dynamic drift data is also compared by the spectrum analysis method. The results show that this method reduces the standard deviation of the static drift data to 44% of the original data, and reduces the angular random walk to 41%. This method can not only reduce the static random drift error in real time, but can also suppress the dynamic output noise effectively..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 612001 (2018)
Relative Pose Estimation Method in Multi-view 3D Reconstruction with Unknown Distortion
XUE Jun-shi, SHU Qi-quan, and GUO Ning-bo
To estimate a relative pose for uncalibrated cameras with unknown distortion in multi-view 3D reconstruction, a robust method with high precision was proposed. Based on the epipolar geometry relationship, the radial fundamental matrix with unknown center of distortion is deduced. The weighted matrix is introduced into To estimate a relative pose for uncalibrated cameras with unknown distortion in multi-view 3D reconstruction, a robust method with high precision was proposed. Based on the epipolar geometry relationship, the radial fundamental matrix with unknown center of distortion is deduced. The weighted matrix is introduced into the coefficient matrix to control the correspondences using to estimate the radial fundamental matrix by singular value decomposition. Then the weighted matrix is updated according to the proposed criterion, and the calculation is performed iteratively. By comparing number of inliers and average distance to epipolar line, the optimal result of the radial fundamental matrix is obtained, determining whether to continue the iterative calculation. After iterative optimization, the final radial fundamental matrix can be used to estimate the center of distortion, distortion parameters and focal length. Experimental results show the efficiency, high precision and numerical stability of the proposed solution and when the mean variance of the noise is 2.5, the mean of distortion parameter error is less than 2% and the focal length estimation error is less than 3.5%..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 612002 (2018)
Extraction City Road Boundary Method Based on Point Cloud Normal Vector Clustering
YANG Wang-shan, CAI Lai-liang, and GU Shu-dan
According to the spatial posture characteristics of the urban road boundary, the method of automatically extracting road boundary point cloud and drawing road boundary lines was set up. Firstly, the spatial storage structure of the space grid point cloud was established, and used the normal vector feature of the whole According to the spatial posture characteristics of the urban road boundary, the method of automatically extracting road boundary point cloud and drawing road boundary lines was set up. Firstly, the spatial storage structure of the space grid point cloud was established, and used the normal vector feature of the whole point cloud in the grid to cluster and split them, and then the improved K-means algorithm was used to extract the road boundary point cloud. Finally, the road boundary line was drawn by the median method. Based on the method, the data of the straight section and the road segment scanning data of the experimental area are selected for analysis. The results show that the proposed method can extract the point cloud of straight line and curve line road boundary and draw the road boundary line without any auxiliary information, it has better extraction effect under the flat condition of the road..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 612003 (2018)
Analysis of the BRDF Characteristics of Dunhuang Radiometric Calibration Site in the Spring
YU Tan-qi, WEI Wei, ZHANG Yan-na, ZHANG Yun-jie, LI Xin, ZHEN Xiao-bing, and SUN Ling
An on-orbit vicarious calibration experiment for FY-4A was formally performed at Dunhuang Radiometric Calibration Site in late April, 2017. In order to meet the needs of the directional corrections in the sensor viewing angle of surface reflectances, the Dunhuang Gobi surface directional reflectances were measured usinAn on-orbit vicarious calibration experiment for FY-4A was formally performed at Dunhuang Radiometric Calibration Site in late April, 2017. In order to meet the needs of the directional corrections in the sensor viewing angle of surface reflectances, the Dunhuang Gobi surface directional reflectances were measured using a portable measurement instrument. The spring directional reflection characteristics of Dunhuang site were qualitatively analyzed and the parameters of bidirectional reflectance distribution function model were inversed based on the RossThick-LiSparseR kernel-driven model. The linear regression analysis was performed for the calculated data and the measured data, the adjusted R-Square of April 26th, 27th and 28th, 2017 are 0.75, 0.83 and 0.85, and the present model had proven to provide a good fit to measured data. The anisotropy factors in the solar principal plane were obtained by utilizing model and compared with historical data of moderate-resolution imaging spectroradiometer BRDF/Albedo model parameters product. The relative deviation of band 2 and band 4 were below 1.56% and the band 5 was below 3.12% when the view zenith angle was less than 40 degrees. The results demonstrate that the constructed model can pretty describe the directional reflection characteristics of Dunhuang site, and verify the reliability of measured data..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 612004 (2018)
Wavefront Reconstruction with Orthonormal Polynomials in a Sparse Subsperture Area
LUO Qian, WU Shi-bin, WANG Li-hua, YANG Wei, and FAN Bin
A stitching algorithm based on orthonormal polynomials in a sparse subsperture area was proposed. In this algorithm, Gram-Schimdt orthogonalization of circular Zernike polynomials is performed by using Mathematica9.0, and the standard orthonormal polynomials, Z-sparse polynomials, which show orthogonality in sparse subA stitching algorithm based on orthonormal polynomials in a sparse subsperture area was proposed. In this algorithm, Gram-Schimdt orthogonalization of circular Zernike polynomials is performed by using Mathematica9.0, and the standard orthonormal polynomials, Z-sparse polynomials, which show orthogonality in sparse subaperture area were established. Wavefront data in sparse subaperture area can be fitting with the new orthogonal polynomials. The experimental results show that the wavefront residuals of peak to valley value and root mean square are 0.071 9λ and 0.007 4λ respectively compared with direct testing result. Therefore the algorithm can effectively stitch the seven subapertureswavefront data of interferometry..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 612005 (2018)
Effect of Packaging on Thermal Stressand Smile of High Power Semiconductor Laser Arrays
CHEN Tian-qi, ZHANG Pu, PENG Bo, ZHANG Hong-you, and WU Di-hai
A ″sandwich″ structure based on copper-diamond is proposed, the thermal stress and Smile of the proposed structure and traditional Cu+CuW hard-solder packaged laser are studied by finite element analysis. Comparison of simulation results shows that the thermal stress of the new package structure is reduced by 43.8% andA ″sandwich″ structure based on copper-diamond is proposed, the thermal stress and Smile of the proposed structure and traditional Cu+CuW hard-solder packaged laser are studied by finite element analysis. Comparison of simulation results shows that the thermal stress of the new package structure is reduced by 43.8% and the Smile value is increased by 95%. When the coefficients of thermal expansion of laser chip and submount are matched, the submount materials with larger elastic modulus can better buffer the thermal stress of the chip. Taking the widely used Cu+CuW hard-solder package structure as an example, the influence of negative electrode and substrate thickness on the Smile of diode laser chip is studied. It shows that when the thickness of the negative electrode increases from 50 μm to 300 μm, the junction temperature of the chip decreases by 2.26 ℃, the Smile value decreases by 0.027 μm, and the thermal stress increases by 22.95 MPa.When the thickness ratio of the substrate to the heat sink is less than 29%, the Smile value increases with the increase of the thickness of the heat sink, and when the ratio exceeds the critical point, the Smile value start to decrease. Hard-solder packaged semiconductor lasers have a maximum Smile value of 3.876μm at a critical thickness of 2300 μm. Hard-solder packaged 976 nm lasers with CuW thicknesses of 300 μm and 400 μm are fabricated. The luminescence spectra are measured. By comparing the peak wavelength shifts, it is found that when the CuW thickness increased by 100 μm, the red shift of wavelength increased by 1.25 nm. According to the effect of temperature and stress on the wavelength, the stress is reduced by 18.05 MPa; the average Smile values of the devices are also measured, which are 0.904 μm and 1.292 μm respectively. Experiments show that the increase in CuW thickness can reduce the stress in the chip, but increase the Smile value..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 614001 (2018)
Analysis of the Influence on the Characteristics of the Prism Laser Gyroscope by Temperature Disturbance
REN Li-na, LIU Jian-ning, and JIAO Ming-xing
The temperature perturbation being considered, the transmission matrixes of the reflected and refracted light beams on the prism surfaces have been modified. According to the self-consistent theory of the laser ring cavity, a physical model of the intra-cavity light transmission has been established considering the temThe temperature perturbation being considered, the transmission matrixes of the reflected and refracted light beams on the prism surfaces have been modified. According to the self-consistent theory of the laser ring cavity, a physical model of the intra-cavity light transmission has been established considering the temperature disturbance in prism laser gyroscope, and the influences on the frequency variation, scale factor and other parameters have been analyzed. The theoretical analysis shows that when the temperature varies from －40℃to 70℃, the changes of the optical cavity-length, frequency offset, and scale factor are 10.04 μm, 0.011MHz and 1.96×10－10, respectively. An experimental system of the prism laser gyroscope has been established whose temperature can be changed, and the experimental results agree with the theoretical values..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 614002 (2018)
Femtosecond Laser Ablation Properties of ZrO2 and Al2O3 Ceramics at Linear and Circular Polarized Light
ZHANG Jun-zhan, ZHANG Yuan-min, LIU Yong-sheng, ZHANG Ying, and LIU Qian
The effects of linearly polarized and circularly polarized femtosecond laser on the ablation threshold of ZrO2 and Al2O3 ceramics at different pulse numbers were investigated. The surface morphology of the ablated craters was analyzed by optical microscopy and scanning electron microscopy and the depth of the ablated cThe effects of linearly polarized and circularly polarized femtosecond laser on the ablation threshold of ZrO2 and Al2O3 ceramics at different pulse numbers were investigated. The surface morphology of the ablated craters was analyzed by optical microscopy and scanning electron microscopy and the depth of the ablated craters was measured by laser scanning confocal microscopy. The results show that the saturation ablation threshold of the two materials at linearly polarized light is smaller than that of circularly polarized light. The saturation ablation threshold of ZrO2 is smaller than that of Al2O3 at the same polarization state. With the increase of pulse numbers, the surface structures of ZrO2 ablation craters develop from disorder to order, and periodic layer annular ripple structures and nanohole arrays are observed at linear and circular polarized light. Compared with linearly polarized light, the effect of circularly polarized light on the depth of ablated craters is stronger, and surface morphology is more sensitive to the change of laser fluence, at the same time, the periodic structures are more obvious..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 614003 (2018)
Er3+ Sensitized Tm3+-Doped Lead-free Bismuth Silicate Glass for 2.0 μm Fiber Lasers
FANG Yong-zheng, JIN Wen-tian, ZHAO Guo-ying, ZHAO Min-yuan, and LIAO Mei-song
Er3+/Tm3+ codoped lead-free bismuth silicate glasses were successfully prepared by conventional melt-quenching method. The energy transfer mechanism and energy transfer efficiency between Er3+ and Tm3+ ions were investigated through absorption spectra and fluorescence spectra. The results show that the Tm3+: 1.8 μm emiEr3+/Tm3+ codoped lead-free bismuth silicate glasses were successfully prepared by conventional melt-quenching method. The energy transfer mechanism and energy transfer efficiency between Er3+ and Tm3+ ions were investigated through absorption spectra and fluorescence spectra. The results show that the Tm3+: 1.8 μm emission is enhanced by codoping Er3+ ions upon 800 nm and 1550 nm excitation. The corresponding maximum emission cross sections are estimated to be 6.7×10－21 cm2 and 7.3×10－21 cm2 on the basis of Fuchbauer-Ladenburger equation, respectively. Simultaneously, both values of 1.8 μm emission bandwidth are about 250 nm. The direct energy transfer microscopic parameter of Er3+: 4I13/2→Tm3+: 3F4 process is calculated to be 16.8×10－40cm6/s. This phenomenon results in the relatively stronger 1.8 μm emission using a 1550 nm pumping source..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 616001 (2018)
Improving B1 Efficiency and Signal-to-Noise-Ratio by a Magnetoinductive Lens for 7.0 T MRI
WU Jie, SHAN Xiang, HU Liang-liang, GUO Kai, GAO Rong-ke, and LI Bing-nan
A metamaterial Magneticinductive Lens (MIL) with negative permeability was designed to improve the Signal-to-Noise Ratio (SNR) for ultra-high field Magnetic Resonance Imaging (MRI). The proposed MIL, fabricated on a FR-4 substrate with a thickness of 0.6 mm, consists of a two-dimensional periodic array of 6×6 capaA metamaterial Magneticinductive Lens (MIL) with negative permeability was designed to improve the Signal-to-Noise Ratio (SNR) for ultra-high field Magnetic Resonance Imaging (MRI). The proposed MIL, fabricated on a FR-4 substrate with a thickness of 0.6 mm, consists of a two-dimensional periodic array of 6×6 capacitor-loaded metallic rings. The equivalent magnetic surface plasmons effect would be achieved in the MIL when it is placed between the RF coil and sample. In terms of the electromagnetic field distribution, the scattering parameters and the equivalent permeability, simulated results reveal that the evanescent harmonics could be heightened. In addition, the evanescent harmonics was excited by the RF coils at the Larmor frequency 297.2 MHz. By loading the MIL, the SNR of MRI images is enhanced about 200% in the sagittal images with a small water phantom, and approximately 58% in the coronal images with a large water phantom. Both simulations and MRI experiments clearly demonstrate that the magnetic field of RF coils could be focused by the metamaterial MIL, which is beneficial to improve the SNR, spatial resolution and detecting depth of MRI..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 616002 (2018)
Preparation and Luminescence Properties of Metal Ions Li+, Na+ and Al3+ Co-doped BaF2∶Eu3+ Phosphors
YE Ying, WANG Lin-xiang, TUO Juan, and ZHAO Hai-qin
The metal ions Li+, Na+ and Al3+ co-doped BaF2∶Eu3+ phosphors were synthesized by the high temperature solid state reaction. The microstructure, morphologies and luminescent properties were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy and fluorescence decay curves, reThe metal ions Li+, Na+ and Al3+ co-doped BaF2∶Eu3+ phosphors were synthesized by the high temperature solid state reaction. The microstructure, morphologies and luminescent properties were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy and fluorescence decay curves, respectively. The experimental results show that the emission intensity at 611 nm of Li+, Na+, Al3+ doped with 9% doping concentration is increased by 4.71 times, 1.51 times and 1.35 times respectively at 266 nm excitation, compared with the single doped 23% Eu3+ sample. After the incorporation of Li+ or Al3+, the lifetime of 5D0 level of Eu3+ becomes longer, and the incorporation of Na+ shortens the energy level life of Eu3+. Compared with BaF2∶23%Eu3+ sample, the luminescence intensities of 9% Li+, 6%Na+, 23%Eu3+ co-doped BaF2 sample and 9% Li+, 12% Al3+, 23%Eu3+ co-doped BaF2 sample increased by 1.73 times and 3.05 times respectively, and the corresponding energy level life was increased..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 616003 (2018)
Controllable Breathers and Multi-peak Solitons in an Inhomogeneous Erbium-doped Fiber System
HE Feng-tao, ZHAN Fei, and SHI Wen-juan
The dispersion-nonlinearity-managed of different types of nonlinear localized waves was studied in an inhomogeneous erbium-doped fiber system, which is described by the coupled generalized inhomogeneous nonlinear Schdinger-Maxwell-Bloch equation. A united nonautonomous solution was obtained by using similarity transfoThe dispersion-nonlinearity-managed of different types of nonlinear localized waves was studied in an inhomogeneous erbium-doped fiber system, which is described by the coupled generalized inhomogeneous nonlinear Schdinger-Maxwell-Bloch equation. A united nonautonomous solution was obtained by using similarity transformation from an inhomogeneous nonlinear Schdinger -Maxwell-Bloch equation. The solution includes lots of the structures of nonlinear local wave in this system. The dynamics properties of breathers and multi-peaks solitons are analyzed from two perspectives, including periodically distributed amplification and phase-shifting nonlinear localized waves. The results show that the novelty structure of nonlinear local wave does exist in an inhomogeneous erbium-doped fiber system and appears diversity under the management of dispersion and nonlinearity, and has a guiding significance in practice theoretically for optical fiber communications..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 619001 (2018)
Wide Tunable Contunuous-wave Mid Infrared Intro-cavity Optical Parametric Oscillator Based on Multi-period MgO∶PPLN
XING Shuang, YU Yong-ji, WANG Yu-heng, FAN Hao-ran, LI Yue, and JIN Guang-yong
A tunable continuous-wave(CW) internal cavity pump optical parametric oscillator(OPO) based on multi poled period MgO∶PPLN was reported. The 3.2~4.1 μm wide tuning mid-infrared parametric light was obtained in real time by changing the poled periods and temperature. The thermal effect and spot modes matching during OPOA tunable continuous-wave(CW) internal cavity pump optical parametric oscillator(OPO) based on multi poled period MgO∶PPLN was reported. The 3.2~4.1 μm wide tuning mid-infrared parametric light was obtained in real time by changing the poled periods and temperature. The thermal effect and spot modes matching during OPO′s wide tuning process were considered. It used a folded type doubly cavities which consisted of 1.064 μm resonator and optical parametric oscillator. The optimum parameters of the cavity structure was determined on account of the numerical simulation and theoretical analysis results. The theoretical simulation of tuning characteristics of OPO was carried out. Based on this structure, the effect of temperature and polarization period on output wavelength was experimentally investigated. It overcame the sever absorption and the quantum loss of MgO∶PPLN in the 3.8~4.1 μm mid-infrared band. Continuous wide range tunable output of 2.78~4.18 μm in mid-infrared radiation was achieved. The tuning range was up to 1.399 μm. The output power of 3.2 μm, 3.5 μm, 3.8 μm and 4.1 μm parametric light was 1.72 W, 1.39 W, 0.79 W and 0.442 W, the corresponding conversion efficiency was 7.17%, 5.4%, 3.1%, 1.84% and 1.72 W..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 619002 (2018)
Photoelectric Characteristics for Graphene/TiO2 Heterojunction Field Effect Photodetectors
ZHOU Quan, ZHANG En-liang, BAI Xiang-xing, SHEN Jun, WEI Da-peng, and WANG Yue-feng
The photodetector based on Graphene/TiO2 heterostructure is fabricated on the substrate of Si wafer, which takes advantage of the light absorption and surface passivation of TiO2 film. The intrinsic photo-response of the photodetector is investigated in a wide range of wavelength. The result indicates that the grapheneThe photodetector based on Graphene/TiO2 heterostructure is fabricated on the substrate of Si wafer, which takes advantage of the light absorption and surface passivation of TiO2 film. The intrinsic photo-response of the photodetector is investigated in a wide range of wavelength. The result indicates that the graphene field-effect transistor photodetectors passivated with TiO2 film deposited on graphene can efficiently prevent the surface channel absorbing the gas molecules, which reduces the dark current drift of graphene field-effect transistor devices. Meanwhile, the graphene channel is sensitive to the changes in charge, and wide spectral absorption characteristics of the composite film can increase the responsivity of graphene field-effect transistor detector significantly. At the ultraviolet band, the photon-generated carries produced by TiO2 layer are mostly injected into the graphene channel, which leads to obvious n-type doping and the highest responsibility of 3.5×105 A/W. On the other side, at the visible band the impurity level between graphene and TiO2 can improve the carrier lifetime of channel compared with the intrinsic graphene. In contrast with the traditional TiO2 arrays photodetectors, the Graphene/TiO2 heterostructure devices have obvious advantage on the performance of response waveband and responsibility..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 623001 (2018)
Opto-mechanical Design of a Spectrally-continuous Radiometer for Surface Reflectance Automation Observation
PAN Yan, LI Xin, ZHAI Wen-chao, LIU En-chao, ZHANG Yan-na, CHEN Yuan, QIAO Yan-li, and ZHENG Xiao-bing
The opt-mechanical design of a Spectrally-Continuous Radiometer (SCR) for surface reflectance automation observation was described. Operating in 400~2 400 nm, the SCR can automatically measure the surface reflectance of radiometric calibration site to get continuous and hyperspectral reflectance data. A calibrated whitThe opt-mechanical design of a Spectrally-Continuous Radiometer (SCR) for surface reflectance automation observation was described. Operating in 400~2 400 nm, the SCR can automatically measure the surface reflectance of radiometric calibration site to get continuous and hyperspectral reflectance data. A calibrated white diffused panel was used as the reflectance standard, and the panel was cut into and out of the optical measurement path through a rotatable mechanical arm. An air-cleaning mechanism was designed to keep the panel clean which is very important for the long-term applicability of the SCR in the field. The static analysis was carried out for the rotating arm using the static structural module of ANSYS WORKBENCH, because the roating arm is prone to failure. The results showed that some stress concentrations located at the rotating shaft position, the deformation was larger as farther away from the rotating shaft, and the maximum deformation can caused a inclination within 0.3°. To verify the accuracy and reliability of the SCR, experiment was carried out with SCR and SVC. The results showed that the reflectance measured with two devices had the same trend, the deviation was generally within ±1%, and the maximum deviation was within ±3.5%, which demonstrated that the SCR could achieve highly accurate reflectance data in automation manners and have broad application prospects in field-based automation calibration and high-frequency calibration for satellite-based remote sensors..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 623002 (2018)
Laser-induced Plant Chlorophyll Fluorescence Lifetime and Spectral Properties Analysis
WAN Wen-bo, and SU Jun-hong
Although the traditional fluorescence spectroscopy method can be used to evaluate the physiological status of plants, there are some measured defects, such as weak anti-jamming, large amount of data in plant remote sensing detection. Aiming at this matter, a fluorescence lifetime imaging technique is presented. The plaAlthough the traditional fluorescence spectroscopy method can be used to evaluate the physiological status of plants, there are some measured defects, such as weak anti-jamming, large amount of data in plant remote sensing detection. Aiming at this matter, a fluorescence lifetime imaging technique is presented. The plant fluorescence lifetime and spectral information are combined to analyze the plant physiological information, and a wide spread of plant physiological status can be measured accurately. The many same fluorescence signal can be produced, while the plant is irradiated by continuous laser pulse in the time resolution measurement method. At the same time, a complete fluorescent signal will be got, while start-up delay time is changed constantly. Then, the plant fluorescence life can be retrieved by deconvolution arithmetic. The spectral information and fluorescence lifetime of living Viburnum awabuki plants was studied. Then, the results show that the plant fluorescence lifetime is linear with chlorophyll concentration. The linear correlation coefficient reaches into 0.9051 in specific range of 0.03~0.06 mg/cm2, and plant fluorescence lifetime is a better description of chlorophyll concentration than the fluorescence spectroscopy in the range..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 630001 (2018)
Photoionization and Photodissociation Study of α-pinene Using Synchrotron Radiation
LIU Xian-yun, XIA Li, WANG Zhen-ya, and ZHANG Wei-jun
To explain the mechanism of ionization of the α-pinene (C10H16), the VUV dissociative photoionization of C10H16 in an energy region of 7.9~15.5 eV has been investigated with a mass-spectrometer method photoionization mass spectroscopy using synchrotron radiation, the dissociation energies and the appearance energies foTo explain the mechanism of ionization of the α-pinene (C10H16), the VUV dissociative photoionization of C10H16 in an energy region of 7.9~15.5 eV has been investigated with a mass-spectrometer method photoionization mass spectroscopy using synchrotron radiation, the dissociation energies and the appearance energies for its fragment ions were predicted. The ionization energy of C10H16 and appearance energies for its fragment ions, C9H+13, C7H+10, C3H+6 and CH3+, were determined with photoionization efficiency spectroscopy. The total energies of C10H16 and its main photofragments were calculated using Gaussian 03 program. The ionization energy of C10H16, appearance potentials for its fragment ions, and the dissociation energies to produce them were predicted using high accuracy energy model. The dissociation energies of some possible dissociation channels to produce those fragment ions were determined based on comparison of determined appearance energies and energies predicted with the Gaussian-03 calculations. According to the results, the experimental dissociation energies were in reasonable agreement with the calculated dissociation energies of proposed photodissociation channels of C10H16..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 630002 (2018)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20